The electronics industry has invested substantially in time and money in the fabrication of components used in connection with bubble device technology. The attraction for this investment has centered on the expectation of a rapidly expanding bubble memory market. These devices serve to span the gap between expensive semiconductors and the mechanically sensitive magnetic disks and tapes.
The substrate material for these devices is composed of a stoichiometric composition of gadolinium-gallium oxides, Gd.sub.3 Ga.sub.5 O.sub.12, commonly referred to as gadolinium-gallium garnet or GGG. Current fabrication techniques for these materials in which a GGG boule or single crystal is grown and then sliced into wafers and polished result in the generation of the order of 80% by-products that are based on relatively expensive starting materials. A method for the recovery and separation of high purity oxides, so that the by-product material could be re-used in the process in a practical manner would aid significantly the economics of production of these GGG wafers.
While the problem of by-product recovery and purification has existed for a number of years in the industry, and attempts to recover by-products have been reported, no economically suitable method is known. For example, U.S. Pat. No. 4,198,231 involves digesting the scrap material and precipitating the gadolinium. However, to recover the gallium, a costly electrolytical deposition step is required. In copending U.S. patent application, Ser. No. 334,719 filed Dec. 28, 1981, now U.S. Pat. No. 4,375,453, entitled "Recovery of Gadolinium and Gallium Oxides", a process involving the digestion of by-product scrap and the precipitation of gadolinium and gallium as the sulfates and oxalates which avoids the relatively expensive electrolysis step is disclosed. The present method provides an alternative to the process described in the above U.S. Pat. No. 4,375,453 and comprises a practical and effective means to recover gadolinium and gallium.